Legendary birds is the collective term used to refer to the trio of Articuno, Zapdos, and Moltres. In the games, they are also known as the winged mirages.

Being the first legendary trio, they set the standards for future trios; that is, they all share similar attributes and—in the case of most of the future trios—are considered equal among themselves. Like the other trios later would, the legendary birds share a master in Lugia (in the anime and some games, at least), as well as two common traits: their Flying-type and their Ability, Pressure. In the anime, Prof. Oak states that Articuno and Moltres combined powers of ice and fire are the source and cradle of the oceans, and that Zapdos' electric energy creates the currents and streams, which is why the three ancient creatures are closely bound to the guardian of the ocean, Lugia.

Pokémon XD: Gale of Darkness

Pokémon Platinum

While it is impossible to capture the legendary birds in Diamond and Pearl (having previously only been obtainable through Pal Park), in Platinum, they have been spotted in the Sinnoh region, which Professor Oak will reveal to the player if they visit him in Eterna City after stopping by Pal Park.

Pokémon HeartGold and SoulSilver

In a surprising turn of events, considering their availability in Platinum, the legendary birds appear once more in HeartGold and SoulSilver, and much as before, are in the same locations as before except for Moltres, who has moved once again, to Mt. Silver. Also due to the Power Plant no longer being abandoned, Zapdos is found outside the Power Plant and will only appear once all 16 Badges are acquired.

Lawrence III succeeds in capturing Moltres first, using strange, electrified rings to contain it, rather than a Poké Ball. He then subsequently kept it on his ship as he hunted out Zapdos, who used Moltres's absence from Fire Island as a signal that it would be able to expand its territory. Shortly after Ash and friends discover this to be the case, however, Lawrence III captures Zapdos as well, drawing the group in as well, due to their boat's similar size to the birds. The group escapes, and, using their Pokémon, manage to free Zapdos and Moltres. The legendary birds are angry, however, and begin fighting, destroying Lawrence III's airship just as he attempts to capture Articuno. The three continue their fight outside, and finally, Lugia reveals itself.

The three birds team up to take down the beast of the sea, however, Lugia recovers and returns to the surface. As Articuno, Zapdos, and Moltres continue to fight, Ash must bring the treasures from their respective islands to Shamouti Island's shrine in order to help Lugia to quell the fighting and prevent the destruction of the world. Though he almost doesn't make it, Ash manages to do so, and the birds make peace, returning to their islands.

In the manga

In the Pokémon Adventures manga

The first of the legendary birds to appear in the manga Pokémon Adventures is Articuno, seen when a group of Team Rocket Grunts invade its abode in the middle of the Seafoam Islands, where it first showed its reluctance to fight by encasing itself in a sheath of ice, which the grunts try to exploit by using a Muk to envelop and carry it whole. In the ensuing battle where Red sends out Gyara, it is terribly troubled by its past experiences of being experimented on by the same villainous team, and is unable to fight back when the Muk rams itself hard against Gyara's body, accidentally breaking Articuno's ice in the process. With its power, Articuno then freezes the disgusting Muk and ignored Red's disturbing its peaceful tenure. In the process, though, it ended up spending much of its strength and was revealed to have been captured.

The next time a legendary bird was seen, it was Moltres, also a new capture of Team Rocket's from Victory Road. Using it to track down and capture the "traitor" Blaine, who had recently given up his position as lead scientist on Team Rocket's experiments (which he conducted on Red's Eevee and Gyara before). With its markedly higher speed and power, it made a joke of Blaine's Rapidash's Fire Spin, and even Gyara's Hydro Pump was dodged with ease, leaving things looking pretty hopeless for the duo. With all bets off, Blaine ordered his Rapidash to take the boy to his laboratory as he held off the fiery bird, borrowing Gyara, where his revival equipment allowed Red's Ancient Amber to revive as an Aerodactyl, which then was able to chip off part of Moltres's right wing. Seeing this, the dastardly Rocket Grunts took a run for it, and no more legendary birds would be seen until the three Pallet Town Trainers attacked the organization's secret hideout at Saffron City.

There, Red found himself fighting an old foe when Lt. Surge revealed himself as part of the Rocket Triad and attacked him at full power with all of his Electrodes and Voltorbs, as well as his Electabuzz and Raichu, dealing grave damage to the boy and Pika, while, due to his insulating underwear, he felt none of the voltage. Gloating about how seemingly limitless his power was with the Rocket equipment, he revealed the source of the ridiculous energy as Zapdos, a Pokémon that they captured in the abandoned Power Plant as the legends foretold. When even Red's Ivysaur, a Grass-type, was badly hurt by a simple ThunderShock, Red exploited how Surge's electric power device was supplying energy through a set of cords and cut them with Razor Leaf, a move Surge thought was futile with his insulating underwear, though little did he know, Red cut the pompous man's clothes as well as the cords, defeating him with his own power (and taking the rubber gloves that would come in handy later).

Right upstairs, Koga was about to finish Blue off with his Golbat when Red arrived and tried to stop him using Poli, only to have the tadpole defeated in an instant. Taking Red as hostage in his schemes instead, Koga then tried to deliver the final blow before Blue revealed his Reflector pendant saved him from Koga's Razor Wind before, and had his Pidgeot take him by surprise. Taking Articuno out at last, Koga slowly froze bits of the two young Trainers before freezing the entire room with a full-power Blizzard which seemingly won him the battle, that is, before Blue and Red thawed themselves out by using Charizard's flames to douse the entire building in fire, and defeated him soon after.

Afterwards, when Red and Green were caught by Sabrina, who had the last remaining bird, Green was tricked into stealing the Badge Amplifier from Red and used his stolen Badges to complete the seven-Badge circle, which resulted in the three birds, two of them called upon by her Kadabra, being merged into a single, three-headed bird, a sight upon which Green (due to her fear of birds) faints upon seeing. When Blue arrives after rescuing Professor Oak and the rest of the Pallet Town residents they kidnapped, the three were seemingly killed when Sabrina sent them plummeting towards the ground before Saur used its vines to form a web, holding them in place. Once it evolved, and after attacking the bird with the other two starters, the three birds were freed and flew away to Red's notice.

After three years of not being heard from, Green revealed she had caught the three birds both to overcome her ornithophobia and use them in the upcoming battle against the Masked Man, where the other two besides Moltres, Articuno and Zapdos, were lent to Red and Blue, respectively, and together they managed to hold their own against Ho-Oh and Lugia, and shortly thereafter the two titanic birds were freed from the evil mastermind's control, so Red and Blue returned the borrowed birds as Red also gave Blasty and Charizard back to his fellow Trainers. They have not been heard from since, so many speculate they may have been released or simply deposited in the Box.

Trivia

In Generation I, the legendary birds all had different base stat totals - Articuno's was 485, Zapdos's was 490, and Moltres's was 495. Since Generation II, when the Special split occurred, all three legendary birds have had an equal base stat total of 580.

Although legends are said to be incapable of breeding, Pokémon Snap shows all three birds being born from eggs, which means they were bred in some way.

The last part of each of the members' names is a number in the Spanish language—one (Articuno), two (Zapdos), and three (Moltres)—and it reflects their National Pokédex order.

Since there were only four tracks of battle music in the Generation I games (wild, Trainer, Gym Leader/Elite Four, and Champion), normal wild battle music is played when the legendary birds and Mewtwo are encountered. In FireRed and LeafGreen, a special remix of the normal wild battle theme is used for the legendary birds, Mewtwo, and the legendary beasts when encountered. However, the legendary birds have never had a battle theme composed specifically for them, unlike the other legendary trios before Generation V.

All of the legendary birds are capable of learning Agility naturally; however, they are able to learn this move at different levels.

If Sinnoh-roaming isn't counted, Moltres is the only one of the trio to change location, and it does so twice.

The legendary birds can be caught in more games than any other legendary Pokémon, as they can be caught in ten main series games in Japan. However, they can only be caught in nine games worldwide, tying them with Lugia and Ho-Oh.

Zapdos is the only one of the trio not to have a double weakness to Rock (or, for that matter, a double weakness to anything).